Hydraulic control apparatus



'7 Sheets-Sheet 1 F. J. FURMAN EI'AL HYDRAULIC CONTROL APPARATUS Feb. 2, 1960 Filed Dec. 31. 1954 INVENTORS FRANK J. FURMAN HUGO A PANISSIDI BY Q ZWM AGENT 1 w 74 a 9 7 5 Q a 5 ,4 7 8 n n & 1& 8 @63 I 3 W w 3. 43 8 4 c 4 V/ A/ \\H o s\\ w I 7 O1 & 8 r I a flyw u a a 9 0 4 .l O w m Q 4 E 2 w m 2 Q 4 7 n w 1 4 w M 8 FIG-.10.

Feb. 2, 1960 F. J. FURMAN EI'AL 2,923,131

HYDRAULIC comor. APPARATUS 7 Sheets-Sheet 2 Feb. 2, 1960 F. J. FURMAN EIAL momma comon. APPARATUS '7 Sheets-Sheet 3 Filed Dec. 31. 1954 MACHINE CYCLE 400 PER MINUTE TIMING CHART v w J E C 5 M .D G u l M A B B 3 A F b PL E N T 12 AUR 0 mm D M BB URSU T A T D A E CC S b HEN M V wRS P CVO R! L PNE .N. P FRENECN EM W W m p U 5; w m M 5m H w u c P m PRINT VALVE 63 ICE; 2

7 Sheets-Sheet 4 IIIIIIIIIIIIIII F. J. FURMAN ETAL HYDRAULIC CONTROL APPARATUS Feb. 2, 1960 Filed Dec. 31. 1954 Feb. 2, 1960 F. J. FURMAN ETA!- 2,923,131

HYDRAULIC CONTROL APPARATUS Filed Dec. 31. 1954 7 Sheets-Sheet 6 nun I y/M/Am zmim il/ mun mgmlk 2,923,131 v HYDRAULIC CONTROL APPARATUS.

Application December 31, 1954, Serial No. 479,112

20 Claims. 01. 60-545) I The invention relates to hydraulic control systems and apparatus and more particularly to hydraulic control systems and apparatus for quickly adjusting or shifting a controlled element or elements to one of a pluralityof preselected positions.

It is one of the objects of the invention to provide hydraulic control apparatus which insures a constant volume of liquid in the control system.

One application of the improved hydraulic control apparatus relates to code rod setup mechanisms or means for wire printers. Heretofore, various means have been proposed to operate code rod units for wire printers which for the most part involve electromechanical arrangements. In these arrangements electrical control pulses are effective to selectively energize certain magnets or the like, which in turn operate to permit positioning of related mechanical links, interposers and the like to actuate or shift an associated code rod to any one of-a predetermined number of positions. After positioning, the code rod is laterally shifted in any suitable manner to axially shift certain of the aligned wires in each matrix to set up the desired character in a remotely located reciprocatable print head. Reciprocation of the print head results. in printing of the selected character on a suitable paper and such printing action returns the character forming wires to their normal retracted positions.

As higher printing speeds are demanded, inertia and wear of the mechanical portions of these setup mechanisms along with other physical limitations become a serious problem. In addition, with the use of a greater number of characters in each line, the direct coupling between the setup mechanism and code rod presents problems with respect to space requirements.

The hydraulic code rod setup mechanism as set forth in this invention utilizes any suitable code rod, lateral actuating mechanism therefor, print head driving means and other necessary control means. This invention is primarily directed to the hydraulic setup means for selectively rotating or axially shifting, or simultaneously doing both, the code rod for a wire printer to one of a predetermined number of positions.

This setup mechanism includes a pair of driven or setup pistons for each code rod or character to be printed. One setup piston is directly connected to the code rod to longitudinally or axially shift the same predetermined increments, while the other is connected to the code rodthrough a rack and pinion to selectively rotate the rod about its longitudinal axis. Each setup piston is hydraulically coupled through a liquid column to an independent set of three control pistons which are disposed in individual control piston chambers. Each control piston is mounted in its chamber to provide different displacements or increments of setup piston movement under the selective control of individual control pulse receiving or setup magnets. In one form, this includes magnetically operated valve means.

The operation of the setup mechanism is synchronized United States Patent tial starting positions.

2,923,131 Patented Feb. 2, 1960 ICC erated pressure supplying or setup valve. During one portion of the cycle the setup valve supplies liquid under pressure to the setup piston to axially shift the same, which in turn reacts through the hydraulic column to displace the control pistons the desired amount and thus limit the setup piston movement. At another portion of the cycle the setup valve is reversed and liquid under pressure is supplied to the opposite side of the previously displaced control pistons to return the same to their ini- This action, of course, results in a transfer of'liquid in the connecting column in the opposite direction andreturns the setup piston to its home position.

Another important feature is that liquid under pressure is periodically directed to the hydraulic column between the setup and control pistons at some point in the op- 25' erating cycle which adds liquid to the column, if necessary, and thereby compensates for any leakage which may have occurred during the previous cycle. Thus a constant volume of liquid is maintained between the pistons to insure accurate operation.

In still another form, a plurality of setup valves have been provided which have been modified to be directly acted on by a related magnet. These valves are shifted in accordance with operation of the related magnets to transfer liquid under pressure from one side to the other of related control pistons to hydraulically shift the setup pistons the desired increments in a somewhat similar manner. -In still other modifications the setup valves are actuated to permit control piston operation which in turn actuate the setup pistons the desired number of increments.

It is, therefore, another object of the invention to provide hydraulic control apparatus for a power transmitting piston which has its limit of travel predetermined.

It is still another object of the invention to preselect control setup means for a power transmitting piston which automatically limits piston travel to one of a plurality of positions. 1

It is yet another object of the invention to provide a variable preselecting control setup means for a power means therefor which involves relatively simple structure.

It is another object of the invention to provide a setup means for a wire printer which involves relatively few low inertia parts.

It is another object of the invention to provide a hydraulic code rod setup mechanism for a wire printer which is capable of high speed operation.

It is still another object of the invention to provide a hydraulic code rod setup mechanism for a wire printer which permits flexibility with respect to the location'of the various control elements.

Other objects of the invention will be pointed out in -the following description and claims and illustrated in the accompanying drawings, which disclose, by way of showing the operation of the various elements "afdif schematic vertical sectional View of a" modified hydraulically operated setup mechanism. H p I v Fig. 5 is a schematic sectionatview 'or'stinanntfier modification of a hydraulically'operated"setupmechanis'm; and,

Fig.'6 is a schematic sectional view of' 'yjetf an modification of the improved hydraulically operated "setup mechanism.

Detail description Referring now to the drawings fora detaileddescription of the improved hydraulically operated-setupgmechanisms, there isshown in Figs. laand lb-a-singlerbr deredposition 'of a'preferr'edformofa hydraulically operated setupmeans 10, Fig. 1a, which isapplied; to a printing. means or 'mechanism 'll, Fig. 1b. This printingi mechanism includes a suitable number of'wire printer units 12 having an array ofwires 13 arranged'in a-ver- 'ticakro'w and'whose upper ends '14, carried by a re-' -ciprocatable print-head -:1'5, 'face'a suitable platen. 16

mounted ona carriage 17. This-1 carriage controls the 'movement'of the paper 18 on which the selecteddata' is to beprinted.- This printingv mechanismymay be oft-he type shown anddescribed in Frank J. Furman et-al.;, ap-

plication, Serial No. 478,650, filed December 30,; 1954. Since the particular means for receiving the data to be printed and the means for reciprocating andlaterally actuating the print headincluding the operation of the associated carriage 17 and the like form no partof this invention, only a general description will hereinafter be-given. 7

As shown in Figs. 1a and 2,. the hydraulically operatedsetup mechanism 10 includes-a body member 19 ,inwhich is housed valve and-piston'mechanisms to be hereinafter described. This-body member may be'disposed within the confines of a suitable liquid retaining sump or reservoir 21 and the lattermay be also adapted to accommodate a liquid pressure generatingmeansin the form of a positive displacement gear pump orthe like 22. The liquid in the reservoir 21 is withdrawn by the pump 22 through a suitable suction connection 23 and is delivered under pressure to a liquid pressure duct or conduit system 24. The system includes a check valve 25, to prevent back flow of pressure should the pump stop, and a liquid pressure relief valve 26 adapted to maintain a substantially constant liquid pressure there- :in. An accumulator 27 may also be connected to the duct system 24 to'compensate for minor pressure fluctuations therein. 7 n

A branch conduit 28 in the pressure duct System24 is directed to the pressure port 29 of a cyclically operated spool type setup valve 31. This valve is shifted or reciprocated by means of an eccentric 32 rotated in timed relation with other machine elements and performs one complete revolution for each print or setup cycle. The sp'ool'v'alve '31 is urged to follow the eccentric cam-32 by'means of a suitablecornpression spring 33'associated therewith. The spool valve'includes a central land34,

for' directing the flow ofhigh pressure" liquid from the 7 pressure port 29 to'eithe'r the associatedleftoi rightlia'nd liquid-conducting chambers; and'a-pair 'of outer spaced lands 35' for controlling the valve exhaust-ports leading to the interior of the' reservoir 21.

As shown, a passage of duct 36 extending from the right-hand chamber of the valve 31 is divided and directly communicates With a pair of cylindrical chambers 37 and 38, wherein reciprocatable driven or setup pistons 39 and 41, respectivelygare mounted. In this instance, the chambers 37 and 38 are formed in ,a housing member 540"s'ecuredto the main body mernb'erd 9.

However, the'sejniembers may be readily separeitedand disposed in different locations When design conditions dictate. Under such circumstances, the' members would behydraulic'ally connected by means of suitable: tubing and the like. It isto be noted both pistons 39 and 41 are adapted for simultaneous movement in the same direction upon the application of liquid under pressure to the passage 36, assuming the appropriate individual control, means, 42" and 43, respectively, therefor have been previously actuated. In addition, each' chamber i's' pro videdwith an up er adjustable'stop means 4410" limit 'upwai-dtravel of the setuppistons "and r'epresentsthe home or starting position of each piston;

The setup" pistons "'39 and"41-"are provided with a re- 1y, each of which hasadb'wer inturnedend 45zr and flda, respectively, I'secu'red adjacent "the central P0111011 of its "related" s'etuf'or driven piston. 'In" this applicationgthe right-hand" drive vv'ifre lti' isdir'ectly' secured "by rneans' of a 'conne'ctingwire '47 toa coderod 43"slideably mounted r a is eapa'bleof' longitudinal o'r a xial shiftingmovement in direct proportion to"*n1ovenientof- -the-related'-'setup on amenity? s'l iiftable frameconstruction fik code fSf-Horizontal' movem'ent ofi the rack 52 r'esult's in rotatied- 6f the ii/k6 i? dildthctide 1'6d 4-3 about its-longb fudinal axis upon' verticaumovement i-or the left hand "setuppist'ori 39. l his motion-translation maybe accomplishedin the standard mannerwhereinthe rod and rack 52 are-secured to the ehdsof a crank armunit 53- pivotal ab'out a By selectively longitudinally shitting the code rod 48 to preselectedincrements, seven in the example shown, and"slectively-rotating=the same about=its longitudinal axisto one of five preselected positions, the various openings in the code rod are capable ofsetting up any one" of thirty-five different -characte'rs. As -generally'sho'wnin Fig. lbythe meansfor later-ally shifting-the code rod 48 includes acontihuously rotating cam mecha- Y n'ism-=55,- which is adapted to oscillate crank arms 56 about-a pair of-parallel spaced axes 57. This provides aparallel =lateral shifting movement to the frame 49 1 carryingthe code rod 48. With the coderod- 48in any one of itsthirty-five possiblepositionspwhen the code rod is shiftedwagainst-the lower ends of thearray of vertically aligned-wires 13,:certain-o-ftheir1 are"sh ifted axially through their respective guide casingsSi-i. This 'actionpi'ojec'tsthe forward ends of the "actuated wires outwardly towardthe-platen l. Under operating-penditionspas soon as -this-takes place,- the print head lS is 'drivenrapidlyjforward and the projecting: ends of the wires print the character on the paper 18. This printing action'returns the projecting wires to their normal positions and the print head 15 is retracted ready for the next cycle of operation,

The particular structural means forsetting up these characters in the wire printer form 'no 'part ofthi's invention, however, the above riieans ared'esc'ribe'd in more detailin the above mentioned Frank I; Fur'rnan application.

Any'suitable means fordrivingthe print-head 15- may "be provided} however, a hydraulic mechanismshown in Figs. 1a and-lb is disclosedmAs shown,- a'painof's'ynchromed ecc'e'iitr ics fiP and 62,- provided with-the" proper phase; angle difference, individually operatc related print or control valves 63' and 64 in"a predeterminedmanner to alternatively direct fluid supplied; by thepressure system 24 through suitable conduits 6 and do. to opposite sides of a print piston 67, Fig. lb, This piston is connected to the print head by means of a drive rod and wire assembly 68 to either hold the piston and print piston retracted, as shown, or, to drive the same rapidly forward and perform the printing operation. This cyclic operation is timed in accordance with the'setup means and other timed elements. The above hydraulic drive mechanism is fully describedand claimed in Hugo A. Panissidi Patent 2,800,885, issued July 30, 1957. Since the particular print mechanism forms no part of the invention, a detailed description 'isnot deemed necessary.

In order to accomplish the above-described'printing operation, accurate movementof the setup pistons 39 vand 41 must be provided to properly alignthe coderod for printing the desired character. In this modification, each setup piston control means 42 an d 43 includes a set 0f three control pistons 71, 72and 73, each of which is- :mounted for reciprocation in related. control chambers 74, 2'75 and 76, respectively. As shown, oneset of control I pistons is connected hydraulically to the lower side of the left-hand setup piston chamber 37 by means of a liquid I passage or channel 7.7 to provide a hydraulicor liquid transfer column, and the other set is hydraulicallyconnected to the lower side of the right-hand setup piston chamber 38 by means of a 'similarpassage to provide a hydraulic or liquid transfer'col'umn 78. 'Thus, it can be seen that each code rod 48 includes two setup pistons 39 and 41 and two sets ofthree control pistons 71, 72 and 73, which when actuated simultaneously or individually in a predetermined or preselected manner, permit code rod movement to print any one of thirty-five possible characters on' the paper 18, Fig.1b. a

Since each code rod 48 for each ordered position is operated in an identical manner, only one of the print positions therefor will be described. Also, since the control means 42 and 431for' the rotational and the longitudinal movement of the code rod 48 are identical in construction and operation, only the longitudinal setup portion for the code rod setup will be described-in detail. However, it is to be understood that the number of code rods 48. utilized depends upon the number of characters to be printed during a cycle of operation and that separate and independent rotational and longitudinal control means for each code rod is necessary.

As shown in Figs. 1 and 2, the individual control pistons 71, 72 and 73 disposed in their separate chambers are each limited in upward travel by means of an adjustable abutment or stop 79. Each of the stops is adjustedto establish different starting or home positions for the assoc ated control pistons to thereby provide different liquid storage capacities in'the lower portions of thechambers. A feature of this control mechanism. is that each control platen is assigned a weighted value in accordance with coded data which is translated into pulses and delivered to any one or any. combination of three setup magnets 80, 81 and 82. These magnets and related control pistons may, in this instance, be labeled 1, 2 and 4, as in- ,dicated on each magnet, to provide a modified binary code handling mechanism capable of accepting and :processing any combination of pulses to move the code rod .48 to any one of seven predetermined longitudinal posi- :tions.

As previously mentioned, with the abutments 79 for .each control piston adjusted. to different positions, the ,liquid receiving space or control chamber beneath each ,,..control piston has a different liquid capacity dependent upon the assigned weighted value. That is, the chamber 1 74 below piston 71 stores liquid equal to l increment of .,setup piston movement, chamber 75 stores liquid equal am 2 increments of movement and chamber 76 stores ..;-1..iq id q a to 4 men s 9i magma At the lower end of each control chamber is a valve means in the fo'rm'of ap'oppet type control valve 83,

having an upw'ardly projecting' guiding stem, normally [urged against'its seat by spring means 84. Each valve normally seals its related'jcha mber." Thus, it is obvious that whenany of these poppet valves are closed, the Itrapped liquid inthe'associated chamber beneath each individual control piston will be effective to maintain the same against its related stop 79 during the hereinafter described setup operation for theassociated piston- 41. Projecting from the lower endof each poppet valve is a drive rod or wire 85 whose outer end .is secured to the free end of a related armature. 86 forming a part of'the associated control magnet. v

The liquid supplied to the lower portions of-the control chambers is directed by the setup valve 31, when the spool therein has been shifted to the right by the eccentric 32, through a passage or channel 87. Opening the pressure port 29 in this direction directs high pressure liquid through the passage 87 to-therbottom side of the poppet valves 83 and opens the samelto supply liquid to any of the control chambers which mayhave been drained duriing a previous cycle, as 'will hereinafter be more fully described. During the interval when pressure is supplied to the lower ends of the Poppet valves 83 to efiect return 1 operation of the control pistons, the passage 36 leading to the top surface of the setup pistons 39 and 41 is connected to drain at one of the exhaust lands on the setup valve 31 to thereby permit return motion of the 7 opened to drain by the other exhaust land 35.

Liquid under pressure is not only continuously supplied to the setup valve 31, but also directed to the pressure port 88 of a supercharging or make-up pilot valve 89. This valve is provided with the usual reciprocatable spool operated by a rotating eccentric 91 to control the supply of liquid to a divided passage or duct 92 terminating at a pair of spacedflsupercharge or make-up check valves 93. Each supercharge check valve is spring biased in opposition to the applied liquid and communicates directly with the related passages forming'the hydraulic columns 77 and 78 between the lower portion of the setup piston chambers 37 and 38, respectively, and the upper surfaces of the associated control pistons. As shown, the hydraulic columns parallel connects the upper portionsof the associated control pistons in the same manner as the passage 87 parallel connects the poppet valves 83. In order to time the application of liquid under pressure to the liquid columns 77 and 78, the supercharge valve 89 is reciprocated by the cam means 91 in timed relation with the other timed elements.

Referring now'to Fig. 3, there isshown a timing chart of the various control or controlled elements which are necessary to properly synchronizethe code rod setup mechanism and printing along with the machine operation. The setup valve 31 has .a motion shown by the curve A and it passes in a cyclic manner from a neutral position to alternatively supply liquid under pressure to the setup pistons 39 and 41 and the poppet valves 83. The second curve B merely indicates the application of liquid under pressure from the setup valve 31 and includes the dotted line C to indicate setup piston motion with respect to time. As shown by the third curve D, the timing of the supercharging valve 89 is such that a liquid pressure pulse is directed over the passage 92 and is made available at the hydraulic columns '77 and 78 once for each code rod setup cycle. This preferably, though not necessarily, occurs at the time when the setup pistons 39 and 41 and the control pistons therefor are in their normal or home positions. As mentioned previously, this liquid pressure pulse causes the appropriate check valve 93 to open shouldany leakage have occurred from the columns'during the previous cycle of operation -and thereby insure a'corlstahtvolume of 'liqui'd in the hydraulic columns 77.. and 78 at all'ti'rnes.

QIhecam operatedmeansfFig. lbgfo'r the code-rod48 which is mounted on. the "frame 49, followsthe "cyclic curve E .and 'provides. a'Tprintv/ire setup"hetwe'enthe ;points F and 16 during 'each "cycle in timed relation with the setup and supereharge valveo eration. ,A'ls'o,.the

lower two curves'H and I 'showthefoperationof the print valves 63farid64, respectively,"which"are"adapted to move oppositely in a tir'ried cy'cliernanner along'with 'the setup valve 31. inthe curve J, at the point closelyv adjacent vvherethe' two valve motions cross the neutral lineKfliq'ui'd under p'ressureis"suppliedto the right-hand side .of the drive piston"6 7 .to :'drivej"the ...print head rapidly forward and then'fthe liquid is reversed to retractzthe same'to its riorinal position.

' ;;Operation 7 7 YA eycle'of operationof the code rod setup mechanism .,is"as'follows: As shown'inFigs. 1a and lb, 'itisassu'md theffgear pump "z lissupplying'liquid under; pressure to Ithe'pres'su're 'conduitfsystem '24. In addition, the cycle of operation is' such that" the setup pistons 39"and *41' and the control pistons 71,72 and73are-intlicirnormaLor i home positions and that thesupe'rcharge valve '89 has just been actuated tosu'pply liquid under pressure t-hroughit-he passage 92 to the'hydraulic' columns 77 and 7840 insure a constant volumeofliquidtherein. After this-occurs, the rotatingecc'e'ntric'fl "automatically cuts 'oif the-supply of liquidand'connects the superchar'ge passage 92 to drain.

Shortly after this 1 hydraulic supercharge -irnpulse, suitable elec'tricalpulsesare applied'to anyone or any com- Ibination of theset'up'mjagnets 80,81 or 82, including- -both the rotational or longitudinal code I rod controls, 'which pulsirigfoi course; is dependent upon'the desired charac- 'ter to be" printed. For the purposes of this description, it will'be assumed the rotational setup magnets are not .pulsed at this portion of the cycle and that onlythe magnet 80, associated with the longitudinal setuppiston 41, is pulsed. This indicates one increment of code rod movement is desired. V g

As magnet'80 is'pulsed, its related armature-86 is attracted and such-action pushes against the drive rod'SS -toopen the associated popp'et valve 83. Upon opening of this poppet valve, theliquid trapped in the chamber'74 .isipermittedto escape to the passage 87 which, -,at-this instant in the cycle, is "directed to drain through-the lefthand exhaust-port in 'the setup valve 31. The residual magnetism inthe pulsed magnet'80 holds the related control poppet valve"83 open.

As thesetup valve 31' shifts through its neutral position, liquidunder pressure is di'rectedover the passage 36 to the upper surfaces of the setuppistons 39 and'41. 'Since the rotational control-poppet valves are closed, the setup 'piston 39 remains against its stop. However, this applied pressure actsltoaxially shift the longitudinal setup piston 41" downwardly, in this instance, due to the open condition of the poppet valve83 associated with the control .piston 71. This downward setup piston movement disvplaces a portion ofthe liquid in' the lower'portion of the chamber 38 which transfers through the liquid column 78.

With no back pressure on the control, piston 71,.downward displacement takes place and forces the liquid thereunder into the now low:pressure passage87. This dis- ..placement continues until the piston .71strikes' the upwardly projecting stem on the related open poppet valve which reacts through the drive rod 85 tof knock 01f the armature 86 of-the magnet 80. Such action returns the poppet'valve to itsseat and stops or interrupts further movement of the control. piston 71. As previously mentioned, the liquid capacity under thisparticular control ,i-piston is -weighted tomprovide one increment of control piston-rnovement. Thus the setuppiston4l is moved hy drulically one increment, which isa"'di'stai'1ce"exactly equal to the displaced liquid m the chamber 74' below 'the control piston 71 and is' then 'hydraulically arrested or stopped byithe liquid-'column 78. 'This translation of the "setup piston longitudinally moves the code rod 48 to a predetermined one increment position. After the above setup of the code "rod takes place, it 4 is laterallynioved against the associated print wires 13 by "the -"cam'55 the liquid therein.

to 'set -up the f desired character to be printed "at the fprinfhead 15,, after whichf'the print piston 67 isactua'ted the previously described manner to print the character'on the paper1 8 carried bythe carriage -17.

.It' is to be noted-that while'thecontrolpistons-72 and "73in'the chambers 75 'and 76,respectively,-were also "acted upon by thepressureapplied from thesetup piston "41, theyrem'ain'against their-stops79 and are not capable of movement. Thisis due 'to'the liquid trapped inthe control chambers 75 "and 76 above' their closed poppet valves. a

After the code 'rod '48 is "returned fromcontact with .the'print'wires '13,"thesetup valve 31 is carnmed'in the oppositedirectionandthe central land 34 therein redirects liqu'idunder pressure through the passage 87 to the lower sides or the parallel connected poppet valves "83. Atthis time," passage '36 leading to the top 'sideof the'setup pistons39 and'41' is connected to'drain through thesame valve. Asliquid under; pressure is applied"-t0 the poppet valves' 83," the valves for the control chambers 75' and 76' will remainseated because the pressure therein is'equal to theapplied; pressure. Howeventhe increased pressure applied to thepoppet' valve for the control cham- "ber 74 opens. the'sa'me to replenish thepreviouslydis- "charged liquid. Asthefliquidflows through the now open poppet valvefthe' controlpiston 74' is displaced upwardly to its normafposition against its stop 79. 1 This return motion displaces the liquid abovethe piston 74 through the hydrauliccolumn78 which'reacts on "the lower side of the setup piston 41 to' return the "same, to its normal or home position against' the'stop 44. When the supplied liquid completely fills the chamber 74, the

pressure onboth sides'of thepoppet valve equalizes, thus the normal spring-bias will close, the valve and'trap 'At' the end ofthiscontrol and setup piston return motron, the supercharg'e valve' 89 is again momentarily opened to supply high pressure make-up liquid over'the 'passage 92 to the liquid-columns 77 and 78 to compensate forany leakage which may have occurred and thereby is capable of printing400 characters per minute. These figures, of course," are given by way of example only because other suitable speeds, both higher and lower, may

be established.

It is obvious that if all three magnets 80, 81 and-82 on the longitudinal setup piston side are pulsed simultaneously, all three poppet valves 83 areopened and the related control chambers 74, 75 and 76, respectively, are connected to'drain. Thus, when liquid under preslsure is applied to the upper surface ofthe setup piston 41, the same will be -displaced a total of seven increments. After'knock-oif of the armatures and later' in the cycle, all three poppet valves are opened bythe application ofliquid under pressure to the passage87 to return all of the control pistons and thus the-setup piston'41a' total of seven inc'rements back to its normal 'home' position, It is"alsoobvi'ous'that by pulsing-any combination" as the fthree" control magnets any desired incremental --movemem of"the-'eoderod-inay"be realized.

linaddition, it should'be -tation of the code rod is desired, the rotational control would be identical. more or less than three' control pistons may be employed. The number used would depend upon the desired piston -movement.

,the pair of setup pistons. jidentical sets of control magnets and valve means operated. thereby which are weighted to provide preselected incremental setup piston movement as previously declear that if incremental romagnets are pulsed in the same manner and'the operation It is to be understood, however, that M odificatio'ns Referring nowto Figs. 4a and 4b there'is schematically shown a modlfied control means for both the lateral .and rotational setup pistons 39 and 41 which are adapted to'either laterally shift and/or rotate the code rod 48 in accordance with pulses delivered to the two sets of control magnets 80, 81 and 82.

Since the setup pistons, control magnets and liquid supply systems are identical .to the previously described modification, like elements are I given like reference characters.

' -As in the first modification, each code rod 48 includes Each setup piston includes scribed. In this construction, three pairs of oppositely disposed control pistons 96 and 97 aredisposed in each ,increment control section, andcontrol or setup spool .type valves 98, 99 and 100 have been provided therefor, ion'e'for each pair of control pistons. control means for both the longitudinal and the rotation- ',al movement of the code rod 48 are identical in construction and operation, only the longitudinal control Since each set of means, shown in Fig. 4b, will be described.

In this construction, the liquid under pressure delivered by the gear pump 22 is applied through parallel passages ,or conduits 24 to the high pressure port 102 at each control or setup valve 96, 97. and 98. Each control valve includes the usual central control land 103 for directing the liquid delivered to the ports 102 and outer spaced lands for controlling fiow through related drain ports which, in

turn, are connected to a common drain passage 104. The spool of each setup valve is biased to the right, in

this instance, by means of a compression spring 105 to normally abut the edge of the associated magnet armature 86.

As shown, the control magnets are all deenergized 'and the armatures 86 therefor are tilted upwardly to maintain their respective spools stationary and shifted to the left, so that liquid under pressure is directed to the right-hand chambers 106 defining cylinders in each of which is mounted one of the control pistons 97. This high pressure liquid holds the control pistons 97 against their associated stops or abutments 107. The opposite side of each control piston 97 is hydraulically connected by means of passages or .ducts 108 to a chamber 109 Y at the right-hand side of the setup piston 41. The champistons 96 are subjected to low pressure, they are maintained shifted to the right against a slide orspacing bar '112 which maintains each pair of opposed'control pistons 96 and 97 in equal spaced relation. The left-hand side of each left-hand control piston 96 is hydraulically parallel connected through a passage 113, which provides a second hydraulic column leading to the left-hand side of the setup piston'41. These control pistons 96 are maintained against the slide bars 112 by the pressure'transmitted through the hydraulic column 113 when the setup piston "41 is moved to'the left.

As in the preteens modification, the meetings slate:

"up valve 89 is-cyclic'ally operated to periodically provide.

high pressure liquid over a conduit or duct 114 to branch passages 115, each of which has a pair of spaced spring-- loaded make-up or supercharge check valves 116 and. 117 therein. These check valves are disposed so that the discharge side of the right-hand check valves'117' are in communication with their respective hydraulic columns 108 and the left-hand check valves 116 communicate with their respective hydraulic columns 113..

It is to be noted that while the application of liquid under pressure to the columns 108 and 113 occurs simultaneously, the right-hand check valve 117 is provided with a spring 118 having a lighter loading than that always urged to the left against its stop 44, defining its home position, and acts to hydraulically prevent piston movement to the right should the valve 116 be opened "by the applied pressure to supply make-up liquid to the second column 113. Both driven or setup pistons 39 and 41 are shown in their normal or home positions.

Each control piston 96 is provided with an adjustable stop means 119. These adjustable stop members 119-are so arranged as to provide the 1, 2 or 4 incremental movement or combination thereof for the related setup piston in the same manner as described in the previous embodiment.

In order to actuate the setup valves 98, 99 and to shift the code rod 48 the desired number of increments,

a bail member 120 is associated with each valve, all ofv which are simultaneously reciprocated in timed sequence: with the normal machine operation in any suitable manner (not shown).

Operation In this particular construction, as the bails 120 move. to the left and approach the end of their inward travcl,. they engage the associated control or spool valves to simultaneously shift the same slightly in the same di-- rection to relieve the end thrust on the related latching;

armatures 86. This action occurs just prior to the. delivery of a control impulse to the control magnets. Should, for example, the magnet 81 be energized at this: time, calling for two increments of longitudinal setup piston and code rod movement, the'related armature 86 is retracted in a downward direction so that it clears: the outer edge of the control valve 99. Now as the bail. motion reverses and moves to the right, the controh valves 98 and 100 re-engage the armaturesof the rc-- lated unenergized magnets 80 and 82, respectively, how ever, the controlvalve 99 follows its bail under influence of the spring loading. As the central land 103 on the valve 99 crosses its pressure port 102, the application.

of liquid under pressure is directed from the right-hand chamber 106 to the left-hand chamber 111 and the outer lands cutoff and open the left and right drain ports,

respectively.

With liquid under pressure now acting against the inner surface of the left-hand control piston 96, the

same shifts to the left until engaged by the associated stop 119 and displaces the liquid therein. This displaced 'liquid in turn reacting through the hydraulic column 113 displaces the setup piston 41 to the right an equal -.tro1.piston 97 whose inner chamber 106 is nowcon nected to drain. Thus, the related right-hand control "211 piston-1971isshifted an equal-number ofincrements and ereacts:on';the.. slide bar ,112 to .aid in holding the left- =thandspiston19fiagainst-its stop 1-19. At :the end-of the ---above-desc ribed. motion, the=code rod 48has been auto- ;matically longitudinally shifted to theposition forthe 'ltozcon'dition'thesameior control yalvenlatching. Upon ;.retu.rn..movement of thebails {120, the released. control ivalve-a99 is shifted: to.the.=left, which in turn. transf.ers

;:the..appl ication :of liquiduunder pressure. from theport 1'02 to .Ethe right-handchamber .106. This liquid transfer :again shifts the:.control.;piston 97 to ,the right against .thetrelated 'stopa107land displaces liquid throughthe :firsthydrauliccolumn 1&8 to return the setup piston :41.to home position against its stop 44. Such .setup piston movement in:turn reacts through the other or I second hydrauliccolumn 113 to also ,returnthe left hand controlpiston97 toiitsnormalor initial position. .'As the -bail pushes .theucontrol valve $9 past. the forward --edge of-the related armaturefifi, thelatter.snapsupwardly and locks the valve imposition. This control valve will remain latched until the related .magnet is vagain.;-p1 1 lse d- =-from the controlsource, regardless .of the.:succeeding reciprocating bail movements.

Here again,.it-1is.obvious that the setup pistonAl may be movedany number of increments from 1107- by selec- -tively energizing any one or any combination of thethree "control magnets 180, i 81 and '82 and that the lop -tion in each instance would .be identical. The same would also apply to operation of the setupspiston 39. After return of the setup and control pistons, liquid under pressure is supplied to both hydraulic columns 103 and 113, in the previously-described "manner, to

-maintain the setup piston3 against its stop.

Fig. 5 schematically represents still another means-for hydraulically setting up the code rod 48 in-which'the operation of a pair of setup pistons 123 .and .124, mounted in a stationary body member-125, have been .modified slightly and-a slightly different control 'valveian'd: setup piston means have been provided.

In this construction, the liquid underpressure isrcontinuously supplied by means of a conduit .126 to the right-hand side of both setup pistons .123 and .124 to contin-uously bias the same to the left. This :biasing -force'of each piston reactslthrough passages defining "hydraulic columns 127 and .128, eachof whichlis parallel connectedto the .left side of separate groups of .three control pistons 129. Each control piston .129 is apro- -vided with an adjustable abutmentor stop member.131.

A 'branch'passage 132 conducts liquid under pressure to parallelconduits leading to the pressure :ports 1340f it-l tC tWO groups of three setup or controlvalves :135, "136- .and 137. Onegroup of valves controls therotational and the other controls longitudinal movement-of .the code rod id/through suitable linkage. Since eachucode rod-48 involves two identicalcontrol portionsvandtvalve control means therefor, only'one will be :described.

"The setup valves 135, 136 and 137 are each:maintained latched to the right, as shown, by an armature:86 and magnet construction identical to that described in Fig; 4 and includes an identical reciprocatablebailmeans "120. With the control or setup valves shifted and Here again, the positionof :the stops 131 and movement :of the icontrol pistons 129 determines the increment of. movement 'of the :driven or setup piston 12.4. With i-theamechanism as shown,. the make-up cr -supercharge .yalve 89 cyclically supplies liquid under ,pressure .overathe :zonduit114 to the make=up check valves 130 associated with their respective hydraulic columns 127 and 128 at predetermined timed intervals during each printingcycle toinsure a constant volume of liquid therein and thereby provide for proper setup piston displacement at all'times. Also, in this instance, the'unbalanced condition of the .opposite sides of the .setup pistons 123 a1id124, due to'the' piston rods '45and 46,

results in .apre ssure differential to the right to always return the setup pistons "123' and .124, respectively, "to

normal or home position against'the'stationary stops 139. The control pistons 129 are urgediagaihst their .respectivestops .131 by the liquid under pressure jsupplied over the line132.

Now assuming thatthe reciprocating bails .120 are moved to the right to relieve the latching pressure'on the related armatures Q86 and any one or all of the control magnets "are pulsed, the related armatures of the pulsed magnets are attracted. As the bails return orgmoveto the left and the control valves of the related pulsed magnets follow sujch movement, the applied 'lii gh pressureliquid to the right-hand side of the effected controlfpistons ,1-29-is .cut off and the related chambers 138 are. connected through the drain ports in the valves .to' aflsuitable drain passage "146. As the drain ports open, the'liquid ,under pressure which is continuously :acting on vthe jightside of setup piston 123, shifts the sameto the'left' and'fhydraulically displaces the effected controlpistons 129 to theright. This shifting movement of the control pistons 129 continues until they strike the end of their related chambers .138 to thus hydraulically limitthe. extent of setup piston movement.

At this point, the setup piston 123 will'have moved the desired number of increments to provide the proper positioning .of the .coderod 48 'for the character selected, after which the wire setup and printing operation occur in the usual manner. "The return movement of the bails 120 shifts the released control valves to the right to relatch the same with the related armature 86 and redirect liquid under pressure to the right-hand side ofthe COHtIOI'PlStODS IZQ, which. in turn are displaced to the left against :their. related .stops 131. This motion, or course, reacts through thehydraulic .column 127 to return the setup piston 123 to its normal orlhomepositio'n against the stop 139,.in .opposition to the constant liquid pressure acting in the opposite direction. This cycle of operation would be repeated in timed relation with otherrequired elements in the printing operation,'which includes, of course, the cyclic application of'high pres- .sure liquid to the hydraulic columns through thescheck valves 130.

Referringnow to Fig. .6, there is schematically disclosed still another modified code rod setup mechanism for the code rod 48. In this construction each lsetufp piston 39 and 41 in turn includes three individual conand 82 includes an armature 148 witha .downturned latch member .149 thereon adapted to engage in a .slot 148:: formed within the periphery of. its.related.control valve and anassociated spring .150 is adapted .to nor- .mally urge-the valveto the left. Undermormal .fde-

energized magnet conditions, the, valves. are .all held to the .righh-as tshown, .andin this condition .the central land 151 of each maintains its central--control-. port.open

through the central ports of the control valves.

is the left-hand liquid chamber 152. This left-hand chamber in each directly communicates with a conduit or passage 153 hydraulically connected in parallel to similar passages by means of a first liquid passage or channel 154. The passage 154 also parallel connects the chambers 146 for the left-hand control pistons 144 to the left-hand side of the setup piston 41 to providea first hydraulic column. A

In the position shown and with a constant voluirie of liquid in the hydraulic column under a suitable pressure, each pair of oppositely disposed control pistons 144 and 145 are hydraulically urged against a related common eccentric 155. These eccentrics are cash designed to provide for different control piston displacements, however, they are synchronized to rotate in 'unison and in phase so that all control pistons simuleffect short-circuited, through the passage 153, that is, as the eccentrics 155 rotate, liquid is displaced from the control piston chambers at one side to the other Since this represents a net zero displacement, the result-isthat the setup piston 41 is not effected; In addition, the setup piston is maintained in its normal orhome position by the trapped liquid in a second hydraulic column 156 communicating with the chamber 157 at the right side of thesetup piston 41. Thus, during this interval,

' the central lands 151 of the control valves block setup piston movement.

At a predetermined point in the printer cycle, supercharge or make-up liquid poppet valves 158 and 159 are sequentially cammed open by means of a double lobed cam 160 and liquid under pressure is supplied to both hydraulic columns 154 and 156, to insure a constant volume of liquid in both. The phase angle 'diiference of the lobes on the cam 160 is such as to apply the high pressure liquid pulse to the column 156 prior to the column 154. This insures the return of the setup piston 41 against its stop and acts as a buffer to prevent the piston from taking some intermediate position, should the pulses be applied simultaneously to each column. eccentrics and the like are rotated in synchronism in timed relation to the machine cycle operation in any suitable manner, not shown.

Now if one or more of the control magnets 80, 81 or 82 are energized, during the proper portion of the printing cycle, the related armatures 148 are retracted from engagement with its associated setup valves, which are urged to the left against a related continuously rotating control valve eccentric 161. These eccentrics are rotated in synchronism with the control piston eccentrics 155,

which, in turn, are continuously reciprocating their related left-hand control pistons 144 are retracted or at the low point on the eccentrics and the right-hand control pistons 145 are at maximum displacement riding on the high portion of the same eccentrics, and the valve operating eccentrics 161 are moving away from their control valves.

With continued valve eccentric movement, communication between the right-hand control piston chamber 147 and the hydraulic column 154 is cut off. At the same time the cutoff chambers 147 are connected to the hydraulic column 156 through the same central port. Now

, as the eccentrics 155 continue to rotate, the displaced liquid in the left-hand control piston chamber under the control of the valve 143 transfers to the related right- In the foregoing, the mechanically operated handchamber 147 in the usual manner. nowevet, the displaced liquid in the other two left-hand chambers 146 can not transfer in this manner due to the cutoff position of the valves 141 and 142; Therefore, this displaced liquid transfers over the hydraulic column 154 to the setup piston chamber and shifts the setup piston 41 to the right a total of three increments. This movement is determined by the total displacement of the two control pistons, which as shown, are operated by eccentrics 155 having different throws.

As the setup piston 41 shifts to its new position, a like quantity of liquid to the right is displaced through the hydraulic column 156 and now opened central control ports of the valves 141 and 142 to the now expanding control piston chambers 147. This influx of liquid causes the right-handpistons to follow their related eccentrics 155, which action, of course, provides the proper space for displaced liquid.

When the eccentrics 155. have displaced the related control pistons a maximum to the left, the code rod has been shifted longitudinally to the desired position, to permit setup of the wiresin the matrix for printing the desired character. The timing of the eccentrics are suchfthat. after print wire setup has occurred, the rotating eccentrics now reverse the direction of control piston movement. Thus the reverse action takes place, that through the hydraulic column 156 to return-the setup piston 41 to its home position. This action, of course, returns the previously transferred liquid back to the lefthand control chambers 146. By the time this point in the cycle is reached, the valve cams 161 will be in a position to shift the control valves 141 and 142 to latch position and the control ports are again disposed in the-original liquid short-circi1iting position. The make-up liquid is supplied to the columns 156 and 154, respectively, as previously described.

This represents a complete cycle of operation and any further control pulses are handled in a like manner to either longitudinally shift and/ or rotate the code rod 48 to any desired position.

. From the foregoing, it can be seen that a hydraulic control means for accurately positioning a code rod or the like has been provided, which involves relatively low inertia elements capable of rapid movement to provide the desired increment of movement of the code rod or output member. Also, that a hydraulic operating means for a code rod or the like has been provided which is supplied with liquid under pressure at some predetermined point in each cycle of operation to maintain constant volumes of liquid in the hydraulic operating means to thereby insure accurate movements of the driven members.

With constructions of the types described, very high speed operation of driven members may be realized which exceeds that provided by conventional electromechanical operating mechanisms.

While the above description of the hydraulic control mechanisms have been specifically applied to the operation of a code rod for a wire printer, it is to be understood this control would be equally applicable to other mechanisms wherein it is desired to selectively shift a driven member to one of a plurality of predetermined positions.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated .by the'scope of the followingclaims. 1

asaanar 15 =What is claimed is: p

1. In cyclically operated hydraulic controlapparatus,

.the combination'of a driven piston having an initialstarting position and whose limit of movement therefromis to be. selectively controlled to one of a plurality of positions,

a control assembly including control pistons for providing the preselected limits of driven piston travel, .means including a hydraulic column for connecting said control pistons to said driven piston, cyclically operated means for hydraulically shifting said driven piston to .oneof the plurality of positions'and for hydraulically returning the .same to its initial starting position through saidhydraulic column, means for holding said .drivenpiston stationary during cyclical operation of said last-named means, and valve means for periodically supplying liquidunderpressure-to said hydraulic column to maintain a constant vol- ,ume ofliquid between said control and driven pistons.

2. In cyclically operated hydraulic control apparatus, the combination of a cyclically operated controlled piston :having aninitial starting position and whose limit of'rnove- -ment therefrom is to be selectively controlled toone of a plurality of positions, a control assembly for said con trolled piston providing for the preselected limits of controlled piston travel during a cycle of operation,.said:'control assembly including a plurality of displaceable control 'pistons,*means for providing a hydraulic column between said control pistons and said controlled piston todirectly limit the extent of movement of said controlled piston, locking means for maintaining said control pistons inactive during cyclical operations to thereby hold said controlled piston fstationary through :said hydraulic 'i'COlllIlll'l, :means iassociated .with 'said last-named means for selectively activating one or more of said control pistons to permitthe displacementofliquid in said hydraulic column, the displacement of said controlled piston" corresponding to 'the "total displacement of the active control pistons, :and

cyclic-ally operated means for returning the activatedicontrol pistons and said controlled piston to *their initial starting positions, said locking means being operative with the control pistons to hold said controlled piston through said hydraulic column.

3. The combination as claimed in claim 2 including means'for applying liquid under pressure'to said hydraulic column to'maintain a constant volume of liquid'therein and insurethe'return of said controlled piston toits startmg position. v

4. The combination as claimed in claim 3 including "means'for timing the application or the liquid'uriderpressure to said hydraulic column to occur after said con- "trolled and control pistons have been returnedto their starting positions.

5. A cyclically operated hydraulic setup mechanism for selectively rotating andlongitudinally translating a code rod for a wire printer to one of a plurality of positions, comprising a'pair of drive pistonshaving startingpositions :and operatively connected to saidcode rod for selectively longitudinally translating and rotating the same in accordance with the desired character to be printed during a cyc'lesof operation, an .independentlyidperable .control assembly .for each drive piston-each control as- Lsemblybeing cyclically operable and including a plurality of.'ind ependently .displaceable control pistons 1 defining a group, :a';passage providing aliydraulic column'nbetween each group of control pistons and the associated drivejpiston to provide for simultaneous movement therebetween,

. locking means associated with each control piston toselectivelyhold said drivepiston during a cyclic operation, means for selectively operating said controlassembly. to

a permitone or. more of said control pistons to permit. hy-

draulicmovement .of the associated. drive piston to the extent permitted .bythe displacementtofthe selectively operated control ,pistons, cyclically .operatedtrneans Lfor .hydraulically returning the selectively goperated-.;control piston and the actuated drivetpistonzto-their initialrpositions, and cyclically operated means for maintaining a substantiallyaconstant volume of'liquid in said hydraulic columns.

' 6..In cyclically operated hydraulic control apparatus, 5 .the combination .of a cylinderhaving a driven piston there- .in normally disposed at a starting position, a control pistonhydraulically movable from first to second positions, a passage providing a liquid pressure transfer 001- .umnbetween said driven and control .pistons to provide for simultaneous movement, valvemeans for hydraulically holding said control piston in the. first position, means for selectively conditioning said control piston displacement means for operating said valve means to'permit movement of .said control piston, and cyclically operated valve means operative to alternately supply liquid under pres .sure to. said driven piston to shiftthe sameand .said .con- .trol piston through said liquid pressure transfer column an amount determined :by .the vresultant control ,piston movement to its second position and to return saiddriven piston to its starting position by applying liquid under pressure to said-control piston to return the same to -.first position, .said valve. means being operative afterreturn of said control piston to hold said driven piston stationary during continuous operation of said cyclically operated valve means.

' -7. Ina cyclically operated hydraulic control system, the combination ofl a cylinder having a drive piston-therein normally disposed at a starting position and cyclically movable to-one'ofra preselected number of positions, control means including a plurality of control pistons each having a starting position, means including a hydraulic ,column-for-conneeting one side of said control pistons to one side .ofsaid drive piston for movement therewithat prese'lected lintervals, independent valve means normally '3 tSfill iQllOld eachcontrol piston in the starting positiorrdnrring cyclic operation of the system, said control pistons :beings operative through. said hydraulic column tohold said drive piston stationary when at their starting positions, means for individually andselectivelyoperating one -.or more independent valve means to condition 'therelated control pistons for operation, cyclically operated means -'for applyingpressure to said drive piston, to move the :same a distance determined by hydraulic movement of the selectively conditioned controlpistons, means for reversing the application .of pressure to return said drive and controlpistons .to their startiugfi positions and means for resetting the selectively operated valverneans to hold :said control .and drive pistonsat the Startingpositions. 8. In a'hydraulic controlsystem, thezcor'nbinationofa cylinderihaving a drive piston thereinnormally disposed .at astartingposition and movable to one-.of a-preselected .:number of positions, "a plurality of control .pistons each .imounted in an individual control chanrber andhavinga starting position, means'including a hydraulicicolumn for connecting one side of'said control pistonstto T0116 side'of said drive piston for movement therewith at preselected intervals, control valve means'associated' with:eacl'r cham- 'ber, said control valve means, when closed, 'beingeflective to hydraulically hold said driveand control ipistons stationary, means for individually and'selectively opening one ormore of said control valves to permitliquidfiow from the related control chamber, means for applying pressure to said drive piston to displace the-same and the 65 "control pistons through said hydraulic column whosevrelated controlvalves have been opened, said actuated control'pistons being operativeupon predetermined displacement to close the associated valve and interrupt further drive ,piston movement, and means for reversing the application of liquid under pressure toreopen the re lated control valves of the actuated controlpistons to applypressurethereto, the actuated control pistons being returned to their starting positions and hydraulically returningsaid-drive piston through transfer of liquid in the actuated liquid column, said control valves being returned to cutoff position after said control pistons have been returned to trap the liquid in said control chambers and prevent further movement of the related control piston.

9. In a hydraulic control system. the combination of a driving piston normally maintained at a starting position Within a chamber and hydraulically movable to any one of a predetermined number of increments, a plurality of control pistons, each disposed in an individual control chamber and adapted to be independently movable therein, means including a hydraulic column for hydraulically parallel connecting one side of said control pistons to one side of said driving piston, individual valve means for each control chamber to trap liquid therein and block control piston movement, means for normally maintaining said valve means closed, means for selectively opening one or more of said valves in accordance with predetermined desired increments of driving piston movement, and means for applying liquid under pressure to the opposite side of said driving piston to displace the same and to hydraulically displace through said hydraulic column the control piston Whose valve means were opened, said displaced control pistons being operative after preselected driving piston travel to engage and close the associated valve and react through said hydraulic column to interrupt further travel of said driving piston, said last-named means being effective after the driving piston travel has been interrupted to apply liquid under pressure to said control valve means to open the same and apply liquid under pressure to said evacuated control chambers to return the displaced control pistons and hydraulically return said driving piston to its starting position.

10. The combination as claimed in claim 9 including means for periodically applying liquid under pressure to said hydraulic column after said driving piston has been returned to its starting position to maintain a constant volume of liquid therein.

11. In hydraulic control apparatus, the combination of a setup piston disposed in a chamber at a normal starting position and movable to one of a predetermined number of positions, a plurality of control pistons, a passage providing a liquid column for hydraulically connecting one side of said control pistons to one side of said setup piston,

an individual liquid control chamber associated with the opposite side of each of said control pistons, said control chambers each being of a different capacity, a control piston valve disposed at the opposite side of said control chambers to seal the same, a magnet including an armature connected to a related control valve, a setup valve having pressure and exhaust ports, passages extending from opposite sides of said pressure port for alternatively connecting the other side of said setup piston and said control valves to liquid under pressure and to drain, said control valves being selectively opened upon energization of the associated magnet to direct the liquid in the related control chambers to drain, means for operating said setup valve intimed sequence whereby after the desired control valves have been opened liquid under pressure is applied to said setup piston to move the same and transfer liquid in said hydraulic column to displace the control pistons whose related control valves have been actuated, said control pistons being operative to engage their related actuated valves to close the same and seal the related control chamber to prevent further movement of said setup piston, said setup valve being operative upon a reversal of movement by said operating means to apply pressure to said control valves to reopen those closed by said control pistons and resupply liquid to the related control chambers and return the actuated control pistons to their starting positions, said return movement of said control pistons reacting through said column to return said setup piston to its starting position, and a valve operative; after the setup and control pistons have returned to iltheir normal starting positions to supply liquid to said hydraulic column to maintain a constant volume therein.

12. In a cyclically operated hydraulic control system, the combination of .a driving piston having an initial position and whose limit of travel is to be selectively controlled, a control piston having a predetermined limit of travel, a liquid passage providing a hydraulic transfer column connecting said driving and control pistons for providing simultaneous movement, therebetween, valve means for hydraulically holding said control piston stationary during cyclic operating of the system, means for seectively operating said valve means to condition said control piston for displacement, cyclically operated means for applying pressure to said driving piston to displace the same and said controlpiston through said hydraulic col-.

umn, said control piston movement limiting said driving piston travel, said cyclically operated means being further operative through said valve means to apply liquid under pressure to said control piston to return the same and to hydraulically return said driving piston to its initial position, and means for maintaining a constant volume of liquid in said connecting passage;

13. In a cyclically operated hydraulic control system, the combination of a driving member normally maintained at a starting position and hydraulically shiftable to one of a plurality of positions, a control piston having a predetermined limit of travel, a passage providing a hydraulic column directly connecting said driving member and control piston for movement in unison, control valve means having a normal position for maintaining said control piston in its starting position to hold said driving member stationary, means for operating said control valve means to condition said control piston for movement, cyclically operated means for applying pressure to one side of said driving member to displace the same an amount equal to the limit of travel of said control piston, said cyclically operated means being operative to transfer the application of pressure to said control piston to return thesame and said driving member to their starting positions, means for'r'eturning' the operated control valve means to the normal position at the end of each operation and means for periodically supplying liquid under pressure to said hydraulic column to maintain a constant volume of liquid therein.

14. In cyclically operated hydraulic control apparatus, the combination of a controlled piston Whose limit of movement is to be controlled, a control piston'assembly having a preselected limit of travel, means for hydraulically connecting said pistons for simultaneous movement, a control Valve for-normally holding said'pistons stationaryduringcyclic operation, means for operating said valve to direct liquid under pressure to said control piston assembly to shift the same'the preselected limit of travel and hydraulically displace said'controlled piston through the hydraulic connection, cyclically operated valve means for hydraulically returning said controlled piston to its starting position by redirecting the application of liquid under pressure to said control piston assembly, means for actuating said control valve to the normal holding position at the end of each cycle of operation, and means'for applying liquid under pressure to said hydraulic connecting'means to maintain a constant volume of liquid ther'ebetween.

15. In'hydraulic control apparatus, the combination of a'setup piston selectively reciprocated within a chamber between a starting position and one of a plurality of forward positions, a plurality of first and second pairsof reciprocatable control pistons, means for holding each pair of pistons in spaced relation, separate passages providing first and second liquid columns extending from opposite faces of said setup piston to opposite faces of each pair of control pistons, a control valve for each pair of control pistons, means forholding said control valves in the first position to direct liquid under pressure to one of each pair of said control pistons to hydraulically maintain said setup piston in its starting position throughsaid first liquid column, means for operating said control valve to redirect the liquid under pressure to the associated second control piston, said second control piston acting through said second liquid column to hydraulically shift said setup piston an equal number of increments, said setup piston displacing liquid on the opposite side thereof through said first column to the first control piston to compensate for the liquid displacement, and means for returning said control valve to said one position to reapply the liquid under pressure to said first control piston to return said setup piston to its starting position through said first column.

16. In a hydraulic control system, the combination of a chamber having a hydraulically operated driving piston therein and having a normal starting position, control means for selectively positioning said driving piston to one of a predetermined number of positions, said control means including a plurality of pairs of spaced first and second control pistons, means for limiting the movement of said control pistons, means for hydraulically parallel connecting one side of said first pistons of each pair to one side of said driving piston to provide a first hydraulic column, means for hydraulically parallel connecting one side of said second pistons of each pair to the opposite face of said driving piston to provide a second hydraulic column, a control valve for each pair of control pistons, means for normally holding each of said control valves in one position to direct liquid under pressure to one side of each of said first control pistons to hydraulically hold the same and said driving piston stationary, means for selectively operating one or more of said control valves to redirect the liquid under pressure to said second control pistons of the actuated valves to hydraulically displace the related second control pistons a predetermined number of increments and hydraulically shift said driving piston through said second column an amount equal to the total control piston displacement, said driving piston being operative to hydraulically shift the associated first control pistons of the operated valves in the direction of the actuated second control pistons through said first hydraulic column, means for returning the operated valve or valves to their original positions to reverse the application of liquid under pressure from said second to said first control pistons to return the same, said first control piston movement acting through said first hydraulic column to return said driving piston to the starting position, said actuated second control pistons being hydraulically returned to normal by transfer of liquid through said second hydraulic column, and means for periodically applying liquid under pressure to said first and second hydraulic columns to maintain a constant volume of liquid therein, said last-named means including means operative to supply liquid to said first hydraulic column prior to said second hydraulic column to maintain a pressure bias on said driving piston in the direction of said normal starting position.

17. In hydraulic control apparatus, the combination of a setup piston normally disposed within a chamber at a starting position and reciprocatable therein to one of a plurality of other positions, a source of liquid under pressure, means for continuously supply liquid to one side of said setup piston to urge the same in one direction, a control piston movable a preselected number of increments, a hydraulic column for connecting said control and setup pistons for simultaneous movement, a control valve means for maintaining said control valve in one position to direct liquid under pressure to one side of said control piston in opposition to the pressure supplied to said one side of said setup piston, means for operating said valve to connect said one side of said control piston to drain whereby the liquid under pressure acting on said one side of said setup piston shifts the same and acts through said hydraulic column to shift said control piston the predetermined number of increments, cyclically operated means for returning said control valve to said one position to reapply liquid under pressure to said control piston to return the same, said control piston acting through said column to return said hydraulic setup piston to its starting position, and means for applying high pressure liquid to said hydraulic column at a predetermined point in the cycle of operation to maintain a constant volume of liquid in said hydraulic column.

18. In hydraulic control apparatus, the combination of a setup piston normally disposed in a chanmber at a starting position and movable therein to one of a plurality of preselected positions, a plurality of pairs of oppositely disposed control pistons each mounted in a control chamber, means defining first and second hydraulic column for hydraulically connecting one side of each pair of said control pistons to opposite sides of said setup piston, control piston cycling means for displacing said pairs of control pistons in synchronism to displace liquid in said control chambers, a control valve associated with each pair of related control chambers, means for reciprocating said control valves in synchronism with said control piston cycling means, latch means for holding said control valves out of engagement with said reciprocating means to provide continuous transfer of liquid between opposite control chambers of related pairs of control pistons, an independently operable magnet for each control valve operative upon energization to release the related control valve to interrupt transfer of liquid between related control chambers, said control piston cycling means being operative through the actuated control pistons to displace liquid through said first hydraulic column to displace said setup piston an equal amount, said displaced setup piston being operative to transfer a quantity of liquid on the opposite side thereof through said second hydraulic column and actuated control valves to the efiected control piston, said control piston cycling means being further operative to return the displaced liquid to said opposite side of said chamber on the return cycle to return said setup piston to starting position, said reciprocating means being operative upon return movement to relatch said control valve in position to permit transfer of liquid between said related control chambers, and means for periodically applying liquid under pressure to said chamber on both sides of said setup piston to maintain a substantially constant volume of liquid therein.

19. The combination as claimed in claim 18 wherein said last-named means includes a pair of liquid make up valves, one for each side of said setup piston, and cam means for sequentially opening said make up valves to insure return of the setup piston to the starting position.

20. In a hydraulic control system, the combination of a driven piston normally disposed within a driven piston chamber at a starting position against a stop and adapted to be hydraulically moved to and held at any one of a predetermined number of positions, a plurality of pairs of opposed control pistons, said opposed control pistons each being disposed in an individual control chamber with each pair of said control pistons being independently displaceable preselected increments, means for reciprocating said pairs of opposed control pistons in synchronism and in the same direction, means for parallel connecting the control chambers of one of each of said pairs of opposed control pistons to one side of said driven piston chamber to provide a first hydraulic column, control valve means for hydraulically connecting the opposed control piston chambers to maintain said driven piston stationary as said opposed control pistons are reeiprocated, means for parallel connecting the other side of said driven piston chamber to said control valve means through a second hydraulic column, means for selectively operating said control valve means to close the hydraulic connection between the control chambers of the actuated control valve means, said first hydraulic column directing the displaced liquid from said effected control chambers to displace said driven piston an equal number of increments, said driven piston displacing a like quantity of chambers, said driven piston being returned to said stop by displacement of the fluid in second hydraulic column during the return stroke of said control pistons, means for actuating said control valve means to hydraulically connect said opposed control piston chambers, and means for periodically supplying liquid under pressure to said first and second hydraulic columns at both sides of said driven piston to maintain a constant volume of liquid in both hydraulic columns, said last-named means being operative to supply the liquid to said second hydraulic column prior to said first hydraulic column to maintain said driven piston against said stop.

References Cited in the file of this patent UNITED STATES PATENTS Mesta Nov. 12, 1895 Staggs May 28, 1929 ,Rosenkranz Jan. 31, 1933 Pennock Nov. 7, 1933 Bell Oct. 15, 1940 Croll Apr. 29, 1941 Morrison Sept. 29, 1942 Silver Oct. 24, 1944 Hughes Mar. 16, 1948 Calvert Oct. 14, 1952 Barrett July 24, 1956 

